This is not pre-initializing the variable that receives the number of
bytes read to 0 which can result in custom VFS implementations
returning an invalid value if they return early from an error or
whatnot.

Public issue https://github.com/mackron/miniaudio/discussions/647

Note that this does not currently work at runtime.

The Cosmopolitan-specific windows.h stuff has now been moved to an
external file in the extras folder:

    extras/cosmopolitan/include/windows.h

To compile with Cosmpolitan it is now required that you add the above
path to the command line when compiling.

The Windows build now compilers with this commit.

This is just an experiment. Cosmopolitan is not officially being
supported.

The Windows build does not compile with this commit.

Public issue https://github.com/mackron/miniaudio/issues/495

Public issue https://github.com/mackron/miniaudio/discussions/637